1. Field of the Invention
The present invention relates to an apparatus for penetrating body tissue. More particularly, the present invention relates to a trocar assembly having a gas pressure system which connects to a gas pressure source to provide an indication when the trocar penetrates the body tissue or to actuate safety means.
2. Description of the Related Art
Endoscopic surgical procedures, that is, surgical procedures performed through tubular sleeves or cannulas, have been utilized for many years. Initially, endoscopic surgical procedures were primarily diagnostic in nature. More recently as endoscopic technology has advanced, surgeons are performing increasingly complex and innovative endoscopic surgical procedures. In endoscopic procedures, surgery is performed in any hollow viscus of the body through small incisions or through narrow endoscopic tubes (or cannulas) inserted through small entrance wounds in the skin. In laparoscopic procedures surgery is performed in the interior of the abdomen.
Laparoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e., provisions must be made to ensure that gases do not enter or exit the body through the laparoscopic or endoscopic incision as, for example, in surgical procedures in which the surgical region is insufflated. Moreover, laparoscopic and endoscopic procedures often require the surgeon to act on organs, tissues and vessels far removed from the incision, thereby requiring that any instruments used in such procedures be both long and narrow.
Typically, after the surgical region is insufflated, trocars are used to puncture the body cavity and provide the above noted cannula used during endoscopic procedures. Generally, trocars used during such procedures include a stylet having a sharp tip for penetrating the body cavity and protective tubes positioned over the tip to protect a patient or surgeon from inadvertent contact with the tip. An example of a typical trocar is described in, commonly assigned, U.S. Pat. No. 4,601,710 to Moll. The trocars typically utilize mechanical designs to achieve the desired protective movement of the tube and/or stylet.
One other type of trocar used to puncture the body cavity has a tip which retracts into the cannula. See commonly assigned U.S. Pat. No. 5,116,353 to Green.
Another type of trocar is described in European Patent Application No. 0 484 725. That trocar has a hollow shaft and a tip at a distal end portion of the hollow shaft formed as a window made from a suitable transparent material, such as glass quartz or glass plexiglass. An optic guide and a fiber optic lighting unit are fed to the tip through the hollow shaft. Typically, the optic includes fiber optic light guides which are fed through the hollow shaft to the tip. The optic ends at an axial distance behind the vertex point of the tip so that the optic illuminates the entire lateral surface of the conical window for observation purposes. In this configuration, the operator has a view of the structures that may be penetrated when inserting the instrument. Thus, the operator can, for example, detect blood vessels before they are encountered by the tip of the instrument and avoid them. More particularly, the operator can observe the distal end of the tip during and after complete penetration of the peritoneum so that the subjacent vessels and structures of the peritoneum are safely negotiated.
The present invention, on the other hand, provides a new and different apparatus and method for detecting penetration of the peritoneum or other body portions with a trocar assembly.